Stub
Implemented 'cond'
Added 'null?'. +passed complex test, see description"

The test program (result = 25):

;; My first Scheme program ever, and as a consequence the most complex
;; Hello World I've ever written.
;;
;; Defines summax, which calculates the sum of squares of a list except
;; its minimum element.
;;
;; 2013-02-01 23:19:30

(begin
      ; Right fold
      (define (fold f z xs)
              (if (null? xs)
                  z
                  (f (car xs) (fold f z (cdr xs)))))
      ; Sum of a list
      (define (sum xs)
              (fold + 0 xs))
      ; binary min
      (define (min a b)
              (if (< a b) a b))
      ; list min
      (define (minimum xs)
              (fold min (car xs) (cdr xs)))
      ; Delete first element equal to p from xs.
      (define (delete p xs)
              (cond ((null? xs) '())
                    ((= p (car xs)) (cdr xs))
                    (else (cons (car xs) (delete p (cdr xs))))))
      ; Map
      (define (map f xs)
              (fold (lambda (x acc) (cons (f x) acc)) '() xs))
      ; ^2
      (define (square x) (* x x))
      ; summax
      (define (summax xs)
              (sum (map square (delete (minimum xs) xs))))
      (summax '(2 3 4)))
Added some list functions